scholarly journals X-RAY DIFFRACTION STUDIES ON AMYLOID FILAMENTS

1968 ◽  
Vol 16 (11) ◽  
pp. 673-677 ◽  
Author(s):  
E. D. EANES ◽  
G. G. GLENNER
Keyword(s):  
Polypeptide Chain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Filament Axis ◽  
Adjacent Chain ◽  
Diffuse Halo ◽  
Sheet Structure ◽  
Regular Manner ◽  
Ray Patterns ◽  
Pleated Sheet

The filamentous protein component of amyloid-laden tissue was studied by x-ray diffraction procedures. The principal features of the x-ray pattern from nonoriented amyloid material consist of a sharp, intense ring at 4.75 Å overlaying a diffuse halo at 4.3 Å, and a broad and less intense ring at 9.8 Å. When oriented, the material gives a "cross-β" x-ray pattern. The x-ray findings are interpreted in terms of a "pleated sheet" structure formed by the amyloid polypeptide chain folding in a regular manner on itself such that adjacent chain segments are laterally arranged in an antiparallel manner. The x-ray patterns from oriented amyloid suggest further that the axes of the chain segments run transverse to the filament axis.

A Mn(II) Metal-Organic Framework Constructed from a Tetrahedral Silicon-Cored Ligand

2013 ◽  
Vol 275-277 ◽  
pp. 2367-2370
Author(s):  
Qing Yu Ma ◽  
Rui Fang Guan ◽  
Guo Zhong Li ◽  
Deng Xu Wang
Keyword(s):  
Single Crystal ◽  
Metal Organic Framework ◽  
Diffusion Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Slow Diffusion ◽  
Sheet Structure ◽  
Metal Organic ◽  
1D Chains ◽  
Organic Framework

A novel metal-organic framework, MnCl2(BIPS)2•2CH3OH•2H2O (1) were synthesized from MnCl2 and a tetrahedral silicon-cored ligand, Me2Si(p-C6H4-imdazol-1-yl)2 (BIPS) under the slow diffusion method. The structure was determined by single-crystal X-ray diffraction. Complex 1 is a 2D sheet structure constructed from 1D chains with 34-atom metallamacrocycles.

Etude structurale par diffraction des RX et spectroscopie IR des hydrates 10 et 8.4 Å de kaolinite

1999 ◽  
Vol 32 (5) ◽  
pp. 968-976 ◽  
Author(s):  
S. Jemai ◽  
A. Ben Haj Amara ◽  
J. Ben Brahim ◽  
A. Plançon
Keyword(s):  
Water Molecule ◽  
Octahedral Site ◽  
Ammonium Fluoride ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Tetrahedral Sheet ◽  
X Ray ◽  
Octahedral Sites ◽  
Sheet Structure

Two hydrated kaolinites, characterized by 10 and 8.4 Å basal distances, were synthesized by treating the kaolinite KGa-1 with dimethyl sulfoxide (DMSO) and ammonium fluoride (NH4F). The X-ray diffraction study was based on a comparison between the experimental and calculated profiles. This study was conducted in two steps: firstly, the study of the 00lreflections enabled the determination of the stacking mode alongc*, the number of water molecules and their positions along the normal to the plane of the sheet structure; secondly, the study of thehkbands, withhand/ork≠ 0, enabled the determination of the stacking mode and the positions of the water molecules in the (a,b) plane. The 10 Å hydrated kaolinite is characterized by two water molecules per Al2Si2O5(OH)4unit, situated at 3 and 3.4 Å from the hydroxyl surface, over the octahedral sites. Two adjacent layers are translated with respect to each other, withT11= −0.38a− 0.37b+ 10n. The 8.4 Å hydrated kaolinite is characterized by one water molecule per Al2Si2O5(OH)4unit, situated at 2.4 Å from the hydroxyl surface and inserted between the vacant octahedral site and the ditrigonal cavity of the tetrahedral sheet. The corresponding interlayer shift isT11= −0.355a+ 0.35b+ 8.4n.

scholarly journals Anomalous reflexions in X-ray patterns

1941 ◽  
Vol 179 (976) ◽  
pp. 1-7 ◽  
Keyword(s):  
Simple Theory ◽  
Monochromatic Radiation ◽  
X Ray Diffraction ◽  
Satisfactory Explanation ◽  
Characteristic Radiation ◽  
X Ray ◽  
Diffraction Patterns ◽  
Ray Patterns

The presence on X-ray diffraction patterns of anomalous reflexions, that is to say, reflexions which cannot be accounted for by the simple theory of diffraction, is almost a commonplace. Many of these effects are no doubt to be ascribed to imperfections in the specimen, strains, etc., but even after these have been taken into account there remain streaks and spots for which there is no satisfactory explanation. The observation of effects of the type considered here is by no means novel; Friedrich (1913) recorded them as radial streaks running through the Laue spots in a photograph of KCl. The extra spots are generally very weak compared with the normal Laue reflexions and indeed may not be observed at all unless the photographs are somewhat over-exposed. They are most easily observed on Laue photographs taken with a tube emitting a characteristic radiation such as the K radiation of Cu or Ag, and their study will be greatly facilitated by the use of powerful sources of monochromatic radiation.

scholarly journals SÍNTESIS DE YAIO3 (YAP) POLICRISTALINO POR EL MÉTODO DE COMBUSTIÓN EN SOLUCIÓN

2018 ◽  
Vol 27 (1) ◽  
pp. 61
Author(s):  
A. Lazo ◽  
C. Paucarchuco ◽  
H. Loro
Keyword(s):  
Combustion Process ◽  
Orthorhombic Phase ◽  
Combustion Method ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
X Ray ◽  
Structure And Morphology ◽  
Palabras Clave ◽  
Diffraction Peaks ◽  
Ray Patterns

Se presenta el método de combustión en solución y su aplicación para la síntesis de YAlO3 (YAP), fueron usados como combustibles para la reacción de combustión y síntesis la urea y glicina, del YAP. Usando las técnicas de difracción de rayos X (XRD) por el método del polvo y microscopia electrónica de barrido (MEB) fueron analizadas la parte estructural y morfológica de las muestras obtenidas. Los difractogramas de Rayos X muestran una excelente correspondencia con lo reportado en la literatura para este material. Se suministran también los resultados de las muestras de material YAlxCrx‐1O3, dopado con Cr3+ con x = 0.001, 0.01, que exhiben picos de difracción dominantes debidos a la fase ortorrómbica de YAlO3 Palabras clave.- YAP, YAlO3, Combustion method. ABSTRACT The solution‐combustion process is presented, as well as its application to the synthesis of YAlO3 (YAP). Urea and glycine were used as fuel for the combustion reaction and synthesis of the YAP. The structure and morphology of the obtained sample were analyzed using the X‐ray diffraction (XRD) powder method and scanning electron microscopy (SEM). The X‐ray patterns showed an excellent agreement with data reported in the literature for this material. Results are also given for samples of YAlxCrx‐1O3 doped with Cr3+, with x = 0.001, 0.01, which showed dominant diffraction peaks due to the orthorhombic phase of YAlO3. Keywords.- YAP, YAlO3, combustion method.

scholarly journals Three New Supramolecular Coordination Polymers Based on 1H-pyrazolo[3,4-b]pyridin-3-amine and 1,3-benzenedicarboxylate Derivatives

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 819 ◽  
Author(s):  
Yun Xu ◽  
Qing-Hua Deng ◽  
Fang Ding ◽  
Ran An ◽  
Dong Liu ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Coordination Polymers ◽  
Supramolecular Network ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Bonding Interactions ◽  
Sheet Structure ◽  
Supramolecular Coordination ◽  
Solvothermal Conditions

Three new supramolecular coordination polymers, namely [Zn(1,3-BDC)(HL)]n (Polymer 1), [Zn3(1,3,5-BTC)2(HL)2(H2O)2]n (Polymer 2), and [Zn9(5-SO3-1,3-BDC)2(L)8(OH)4]n (Polymer 3), were synthesized under solvothermal conditions, based on 1H-pyrazolo[3,4-b]pyridin-3-amine (HL) along with 1,3-benzenedicarboxylate (1,3-BDC) and its derivatives, such as 1,3,5-benzenetricarboxylate (1,3,5-BTC) and 5-sulfo-1,3-benzenedicarboxylate (5-SO3-1,3-BDC). Polymers 1–3 were characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction (PXRD), and single crystal X-ray diffraction analysis. Polymer 1 exhibited a two-dimensional (2D) 4-connected sql net. The neighboring 2D nets were further linked into a 3D supramolecular network by hydrogen-bonding interactions. Polymer 2 displayed a 3D (4, 4, 4)-connected network, which was further stabilized by R 2 2 (14) and S(9) hydrogen-bonding rings along with π–π interactions. The 2D sheet structure of Polymer 3 was constructed by novel quasi-linear nonanuclear Zn(II) units, which further extended into a 3D supramolecular structure by hydrogen-bonding interactions. The solid-state photoluminescence properties of Polymers 1–3 were also investigated.

Fibril formation through self-assembly of a simple glycine derivative and X-ray diffraction study

2020 ◽  
Vol 235 (1-2) ◽  
pp. 47-51
Author(s):  
Arpita Dutta ◽  
Suven Das ◽  
Purak Das ◽  
Suvendu Maity ◽  
Prasanta Ghosh
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
High Resolution ◽  
Diffraction Study ◽  
Self Assembly ◽  
Van Der Waals Interactions ◽  
Base Catalyst ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sheet Structure

AbstractN-(N-benzoyl glycinyl)-N,N′-dicyclohexylurea was synthesised by conjugating N-benzoyl glycine and dicyclohexylcarbodiimide (DCC) using triethylamine as base catalyst. A single crystal X-ray diffraction study reveals that the compound self-assembles into a supramolecular sheet structure by intermolecular N–H · · · O, C–H · · · O hydrogen bonding and non-bonding van der Waals interactions. A high resolution transmission electronic microscopic (HR-TEM) image of the compound exhibits formation of fibrils in the solid state.

scholarly journals THE STRUCTURE OF ACTIN-RICH FILAMENTS OF MUSCLES ACCORDING TO X-RAY DIFFRACTION

1956 ◽  
Vol 2 (1) ◽  
pp. 71-85 ◽  
Author(s):  
Cecily Cannan Selby ◽  
Richard S. Bear
Keyword(s):  
Large Scale ◽  
Adductor Muscle ◽  
X Ray Diffraction ◽  
Cell Width ◽  
X Ray ◽  
Filament Axis ◽  
Repeat Structure ◽  
Diffraction Patterns ◽  
The Individual ◽  
Macromolecular Component

From analysis of moderate- to small-angle x-ray diffraction patterns, in the light of similar experience with paramyosin, has been derived the following description for the structure of actin-rich filaments in "tinted" portions of the adductor muscle of the clam, Venus mercenaria: 1. Some 11 diffraction maxima, widely streaked along layer lines and occurring at moderate diffraction angles (spacings 7 to 60 A) appear to be accounted for as (hk) reflections of a net whose cell elements are, for dry material: a ≑ 82 A, b = 406 A (filament axis identity period), and γ ≑ 82° (angle between a and b axes). These reflections follow a selection rule which indicates that the net cell is non-primitive and contains 15 equivalent locations (nodes) arranged as shown in Fig. 5. An alternative net has b' = 351 A and 13 nodes per cell. 2. Another interpretation rolls the net into a large-scale helix and places the 15 (or 13) nodes along 7 (or 6) turns of a helical locus projecting 406 (or 351) A along the filament axis. Whether considered to be built of planar-net or helix-net cells, the individual filament contains a single cell width transverse to its axis. Transverse filament dimensions are, therefore, in either case similar (50 to 100 A). 3. Consideration of existing electron-optical, physicochemical, and x-ray diffraction data regarding isolated actin suggests that the net cell is built of rods, each containing in cross-section from one to four actin molecules which run parallel to or twisted about rod axes that extend at 12° to the filament axis along the (21) diagonals of the cell. Depending on monomer shape, 2 to 15 monomers furnish length to reach across two cells, and the actin molecules are built into each rod in such a way as to repeat (or nearly repeat) structure 15 (or 13) times along the double cell length. Further details of intra-rod structure cannot be suggested because of lack of wide-angle diffraction information. 4. The actin system is sensitive to treatment of the muscle with ethanol. Concentrations of 5 per cent or greater abolish the net reflections. Other solvents—water, benzene, ether, pyridine, acetone—do not alter the pattern materially. 5. Two other reflections, occurring at the first and second layer lines of an axial periodicity of about 400 A, do not clearly belong to the actin-net system. They represent either a superstructure built upon the filaments by parts of the actin molecules themselves or by incorporated other molecular species, or they arise from an additional macromolecular component (possibly myosin, or its homologues or fractions) of similar axial periodicity.

Infra-red spectra and structure of proteins

1959 ◽  
Vol 249 (1257) ◽  
pp. 147-172 ◽  
Keyword(s):  
Polypeptide Chain ◽  
Critical Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fundamental Frequencies ◽  
Deuterated Proteins ◽  
Infra Red ◽  
Structure Of Proteins ◽  
Red Radiation ◽  
Exact Positions

The Infra-Red spectra of thirty-seven proteins have been observed between 650 and 3700 cm -1 . Several of the bands found common to them all had not been reported proviously and some other bands appear to be common only to those believed to exist in a folded configuration. A critical study of the exact positions of the bands near 1650 and 1550 cm -1 indicates that the frequency criteria developed for distinguishing a from β polypeptides cannot be reliably applied to proteins. Spectra obtained with polarized infra-red radiation confirms the view that in proteins where the polypeptide chain has a coiled (α) configuration, the NH stretching and the Co stretching bands have parallel dichroism and that the amide II band (near 1540 cm -1 ) has perpendicular dichroism: However, the counter part of the amide II band near 1240 cm -1 showed little dichroism in α proteins, but marked parallel dichroism in β proteins. The spectra of several deuterated proteins have been investigated; the results are of considerable value in making assignments of fundamental frequencies. Studies of deuterated silkworm gut using polarized infra-red radiation showed dichroic ratios of several key bands in proteins have been used to make quantitative tests of various polypeptide chain configurations which may exist in proteins. Satisfactory agreement was found in some cases with models based on X-ray diffraction data.

scholarly journals Effect of Particle Size and Sintering Temperature on the Formation of Mullite from Kyanite and Aluminum Mixtures

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
F. R. Barrientos-Hernández ◽  
M. Pérez-Labra ◽  
A. Lobo-Guerrero ◽  
M. Reyes-Pérez ◽  
J. C. Juárez-Tapia ◽  
...  
Keyword(s):  
Particle Size ◽  
Open Porosity ◽  
Sintering Temperature ◽  
Thermal Transformation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Free Silica ◽  
Effect Of Particle Size ◽  
Α Al2o3 ◽  
Ray Patterns

The effect of particle size and sintering temperature of the mixtures of kyanite and metallic aluminum related to the thermal transformation of kyanite into primary mullite and free silica was studied. In addition, the reaction between α-Al2O3 (in situ produced by aluminum oxidation) and the silica was obtained in cristobalite structure from kyanite to obtain secondary mullite. The kyanite powders were milled by 0.5, 3, 6, and 12 hours and then were mixed with aluminum powder, which were previously milled by 3 hours. After that, the powders were characterized by X-ray diffraction technique (XRD), scanning electronic microscopy (SEM), differential thermal analysis (DTA), and thermogravimetric analysis (TGA), and the particle size was determined in a centrifugal analyzer particle size Shimadzu model SA-CP4. The mixed powders were pressed uniaxially into cylindrical samples (compacts), and then sintering was conducted at 1100, 1200, 1300, 1400, 1500, and 1600°C; these samples were characterized by XRD, SEM, and thermodilatometry analysis (TD); density and open porosity measurements were performed by the Archimedes method. The samples were thermally etched to observe the microstructure, which consisted of mullite equiaxial grains contained in a glassy phase. It was observed that the nonmilled kyanite mineral becomes into mullite plus silica at temperatures between 1400 and 1500°C. When the particle size was reduced at sizes less than 1 µm, the transformation temperature was low until 200°C; the X-ray patterns of the sintered samples at 1400°C, ground for 6 hours, showed mullite peaks with small reflections of cristobalite and α-Al2O3, and these samples exhibited high density and low open porosity.

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